Local Multiple Pressure Zone Fresh Water Storage and Supply System

ABSTRACT

An autonomous fresh water storage and supply system for a local community, able to meet the water demand for all kinds of situations even under an emergency circumstance and always able to have a five-day fresh domestic water demand storage in its reservoir. It also has multiple pressure zone water distribution capability. In addition, the water pressure of system can be adjusted to the different setpoints by changing VFD pump output pressure. The electrical power of the water station has both regular power supply from the utility line and backup power from a diesel engine generator. All control instrument devices should be connected to an All in One PC terminal and Human Machine Interface (HMI). All water qualities should be frequently monitored and tested to meet the local water code requirements.

BACKGROUND Field of the Invention

The present invention relates generally to a local fresh domestic water storage and supply system that has multiple adjustable pressure zones.

Description of the Related Art

This system can keep the water in the local storage tank always fresh for emergency water demand in case the water system is disconnected to the city water supply system by nature disaster or operational accident. The use of emergency water storage system at local area has been expected for many years. However, there is little progress in keeping the stored domestic water fresh for a long period within the water storage system. None of previous invention can keep water always fresh to meet local water demand wider emergency water supply circumstance.

SUMMARY

This water system can provide fresh water to the people during the catastrophic time, such as earthquake or city water contamination period when city water supply is no long available to user. The present invention has a fully automatic system combined with a high pressure water supply pump station, a low-pressure water circulation pump station and a fresh water tank at the local area with an automation control panel that has the pressure modulating and autonomous monitoring functionality to manage water pressure limitation constraints and allow water to flow between different water pressure zones and integrate them into a single homogenous water distribution system to remedy local water flow deficiencies in reliability and capacity for all kind of situations especially in an emergency condition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a system flow diagram that comprises of one water tank, three low pressure Variable Frequency Drive (VFD) pumps in parallel, two high pressure VFD pumps, one pressure reducing valve (PRV), one tank level control valve, one flow meter, two pressure gauges, two pressure transducers, one Programmable Logic Controller (PLC) and one Personal Computer for Human Machine Interface (HMI).

FIG. 2 shows the operation curve of three low pressure pumps (#7) in a parallel set (See FIG. 1 for component number) and the pump (#7) operation pressure set point (B psi) and the PRV (#15) opening set point pressure (F psi).

FIG. 3 shows the operation curve of two high pressure pumps (#6) in a parallel set (See FIG. 1 for component number) and the pump (#6) operation pressure set point (G psi); Also, the pump (#6) is energized at pressure E psi (=G−15 psi).

FIG. 4 shows that the pump is operated with variable—speed drive which adjusts the speed of the electric motor and changes the pump curve. The pump variable speed drive is applied to control the required variable flow demand at the local water system at a constant output pressure set point. For example, in this figure, the pump operation set point X psi is 55% pump maximum head pressure. The pump, at 60% speed, can provide 0.33 design flow, at 80% speed, it can provide 0.68 design flow, and at 100% speed it can provide 0.91 design flow. In this particular case, X psi could be substituted by B psi for low pressure pump and by G psi for high pressure pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention relates to an application of parallel pumping. When pumps are applied in parallel, each pump operates at the same head, and provides its share of the water supply system flow at pressure setpoint B (psi). (FIGS. 1 & 2)

When system flow exceeds design flow of three parallel pumps the output pressure of pump will drop to certain degree per pump curve of parallel operation. Based on designed sequence of operation the pressure reducing valve pressure setpoint F is 5 psi below the parallel pumping system setpoint at B (psi). (FIG. 2)

When water supply system demand increases the pump output pressure will drop 5 psi from setpoint pressure B (psi) to point F (psi) per parallel pumping curve and Pressure Reducing Valve (#15) will open and provide additional flow to meet the peak water demand in order to reduce the pump size and its energy consumption. (FIG. 1)

At upstream of pressure reducing valve there is the high-pressure zone of water at the pressure of G (psi). (FIGS. 1 & 3)

In the high-pressure water zone, two high pressure pumps will be energized when the city water main pressure is 15 psi below its normal pressure at D psi (adjustable) where high pressure pump can run only one individually or two together in parallel depending on the local community water demand to maintain high pressure zone water pressure above its setpoint pressure E (psi). (FIGS. 1 & 3)

High Pressure Pump has an Energizing Setpoint pressure E=(D−15) (psi) and an Operation Pressure Setpoint G=D>(B+25) (psi). (FIGS. 1 & 3)

The centrifugal pumps for this invention are also operated with variable—frequency drives, which adjust the speed of the electric motor and change the pump curve. In this application, the controller of pumping system and the variable frequency drive are applied for the pumps to meet the required variable flow demand of water system at a constant output pressure (adjustable). One of requirements of this design is to maintain a pump output pressure setpoint for the variable flow demand of the local water supply system. The setpoint pressure is sensed at the downstream of check valves (#4) on the output manifold of parallel pumping set. It is far more likely that a small incremental rise in demanded supply flow will have a corresponding small increase in pump speed to maintain a constant output water pressure setpoint of B (psi), for the low-pressure pump system and G (psi), for the high-pressure pump system. (FIGS. 1, 2, 3 & 4)

TABLE OF DRAWING ELEMENTS

-   1. Water Tank -   2. Water Mixer Motor -   3. Level Sensor and Transducer -   4. Check Valve -   5. Shut Off Valve -   6. High Pressure Pump -   7. Low Pressure Pump -   8. Pressure Gauge and Transducer for High Pressure Pump Head Control -   9. Flow Meter and Transducer for Pump Flow Testing -   10. Butterfly Valve -   11. Electronics Pressure Sensor and Display -   12. Solenoid Tank Level Control Valve (Water Filling Valve that has     both shutoff and pressure reducing functions) -   13. Flow Sensor for Water Usage Measurement -   14. Pressure Gauge and Transducer for Low Pressure Pump Head Control -   15. Pressure Reducing Valve -   16. Drain -   17. Water pipe -   18. Variable Frequency Drive -   19. Over Flow -   20. Chemical Injection Pot for Tank Washing -   21. Programmable Logic Controller (PLC) & Human Machina Interface     (HMI) -   22. Flexible Pipe Connection 

1. A system to storage and distribute fresh domestic water with various water pressure zones at a local user site through one water tank, two parallel high pressure VFD Water pumps, three parallel low pressure VFD water pumps, one pressure reducing valve, one tank level control valve and a series of Shut off Valve (SOV) and check valve.
 2. This system can keep the water in the tank always fresh with a 5-day (adjustable per user) turnover rate. Given the daily local water usage is A gallons, the tank volume shall be 5×A gallons.
 3. The system is able to integrate different pressure zones to one homogenous water system to meet multiple purpose water usage and demand and to carry out an autonomous local water distribution system with computers and electronics devices such as Programmable Logic Controller (PLC) and Uninterrupted Power Supply (UPS) battery. 